"Yes" Was My Answer

Yesterday, I sat with a friend in a restaurant, in front of each of was this (or so):
It was at that moment that the guy next to me turned to me and quizzically asked:

"Is that a burger?"

Seriously, this happened. My life became a "Snappy answers to stupid questions" Mad magazine feature.

Why would someone ask this question? Some suggestions:

1. He is suffering from meat focused Alzheimer's disease.
2. New York City is much more different from the rest of the country than I realize. Where he is from they're called "Liebermans."
3. He was referring to the fries and I should have said "no."

If you have other possibilities, comments them.